查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0060" view="all">A simple theoretical model has been developed for the solvent extraction of cations with different oxidation states varying from +1 to +4 using acidic extractants. The basic assumption behind this theoretical model is that the cationic species (M<ce:sup loc="post">n+</ce:sup>) will exist in ionic form and not form any complexes in the aqueous phase. A direct relationship between the concentration of metal ions in the aqueous phase and that in the organic phase was developed for trivalent and tetravalent cationic species. Using this model, the distribution isotherms were plotted for a given set of conditions. The effect of pH and equilibrium constant on the distribution isotherms were represented in three-dimensional form for trivalent and tetravalent cationic species. Consistent with expectations, the results suggest that with increasing pH and an increasing equilibrium constant one finds an enhancement of the extraction of cationic species for a given set of conditions. The calculations were performed in the pH range of 1 through 3 because for higher pH values, the pH shift accompanying the extraction is significant and thereby affects the mass balance equations. A comparison of the distribution isotherms shows that the total metal ion concentration to extractant concentration ratio determines the distribution behavior of metal ions with different valency. At low total metal ion concentration to extractant concentration ratio, the distribution coefficient was higher for higher oxidation state cations under similar experimental conditions, and this trend started to reverse when the total metal ion concentration to extractant concentration ratio was increased.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0070" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">Theoretical models for the solvent extraction of cations</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">A mathematical relationship between [M<ce:sup loc="post">n+</ce:sup>]<ce:inf loc="post">aq.</ce:inf>and [M<ce:sup loc="post">n+</ce:sup>]<ce:inf loc="post">org</ce:inf>.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">Explicit algebraic expressions for the isotherms developed</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">The effects of pH and K illustrated in 3D form for n=+3 and n=+4</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0090" view="all">To elucidate how phosphoric acid (H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>) as a depressant achieves selective separation of apatite and dolomite, the flotation response of these minerals was investigated using both single and mixed mineral flotation. Microflotation results demonstrated that H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>exhibits a selective depressive effect on apatite. Flotation kinetics analyses also revealed that the presence of H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>increases the dolomite/apatite selectivity index significantly. The adsorption mechanisms were examined using zeta potential tests, X-ray photoelectron spectroscopy, solution chemistry analysis, and thermodynamic analysis. H<ce:inf loc="post">2</ce:inf>PO<ce:inf loc="post">4</ce:inf><ce:sup loc="post">?</ce:sup>was found to be the pivotal ion for depressing apatite under slightly acidic conditions (pH=5.0–6.0), where the separation of these minerals most effective. H<ce:inf loc="post">2</ce:inf>PO<ce:inf loc="post">4</ce:inf><ce:sup loc="post">?</ce:sup>reacts with free Ca<ce:sup loc="post">2+</ce:sup>to depress the acidolysis of apatite and promote the formation of aqueous CaHPO<ce:inf loc="post">4</ce:inf>. H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>chemisorbs onto apatite surface by the formation of aqueous CaHPO<ce:inf loc="post">4</ce:inf>and Ca(H<ce:inf loc="post">2</ce:inf>PO<ce:inf loc="post">4</ce:inf>)<ce:inf loc="post">2</ce:inf>, with the former being the major species to depress apatite. Moreover, dissolution of Mg<ce:sup loc="post">2+</ce:sup>and Ca<ce:sup loc="post">2+</ce:sup>from the dolomite surface is thermodynamically more favorable than that of Ca<ce:sup loc="post">2+</ce:sup>from the apatite surface. As Mg(H<ce:inf loc="post">2</ce:inf>PO<ce:inf loc="post">4</ce:inf>)<ce:inf loc="post">2</ce:inf>is soluble, H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>only exhibits a weak depressive effect on dolomite. Further, the collector (sodium oleate) maintains excellent dolomite floatability in the presence of H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>, because chemisorption of the collector on the dolomite surface is enhanced by reaction with abundant Mg<ce:sup loc="post">2+</ce:sup>. Therefore, H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>selectively depresses apatite in the apatite/dolomite flotation system.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0095" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>selectively depresses apatite by our flotation and kinetics analyses.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">Acidolysis reaction on dolomite is thermodynamically more favorable than apatite.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">H<ce:inf loc="post">3</ce:inf>PO<ce:inf loc="post">4</ce:inf>depresses the acidolysis of apatite by the preferable formation of CaHPO<ce:inf loc="post">4</ce:inf>.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">Reaction of abundant Mg<ce:sup loc="post">2+</ce:sup>and NaOL enhances collector's
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0080" view="all">The collecting ability of dodecylamine (DDA) and dodecyltrimethylammonium chloride (DTAC) as two cationic collectors was investigated in the flotation of pyrolusite and calcite by carrying out the flotation experiments, FTIR analysis, zeta potential tests and contact angle measurements. The single mineral flotation experiments show that the maximum differences between the floatability of pyrolusite and calcite occurring at a pH of 7.5 in the presence of DTAC is more than that of DDA. This means that DTAC acts more selectively than the DDA collector. In the microflotation experiments carried out on the artificially mixed minerals, the MnO content and recovery in the pyrolusite concentrate obtained by DDA collector is greater than that achieved by DTAC. As evidenced by ore flotation results and contact angle measurements, in the presence of both collectors, sodium carbonate acts more effective than calcium chloride as calcite depressant agents. In the ore flotation experiments, a pyrolusite concentrate containing higher MnO grade and recovery is obtained using DDA collector in comparison with DTAC. These results indicate that the collecting power of DDA is significantly more than DTAC collector. FTIR analysis and zeta potential tests show that both collectors adsorb on the surface of pyrolusite and calcite through the electrostatic interactions. Also, these analyses indicate that the adsorption of DDA on the surface of both minerals is greater and stronger than that of the DTAC collector.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="graphical" xml:lang="en" view="all"><ce:section-title id="st0010">Graphical abstract</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0015" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0015">Highlights</ce:section-title><ce:abstract-sec id="as0015" view="all"><ce:simple-para id="sp0090" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">The collecting ability of DDA is higher than that of DTAC.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">In the flotation of pyrolusite from calcite, DTAC acts more selectively than DDA.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">DDA and DTAC adsorb on the surface of both minerals through electrostatic forces.</ce:para></ce:list-item><ce:list-item id="li0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">The adsorption density of DDA on the surface of both minerals is more than that of DTAC.</ce:para></ce:list-item><ce:list-item id="li0025"><ce:label>?</ce:label><ce:para id="p0025" view="all">Using depressant agent, the selectivity of flotation with DDA is greater than with DTAC.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
查看更多>>摘要：<![CDATA[<ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0005" xml:lang="en" view="all" class="author"><ce:section-title id="st0005">Abstract</ce:section-title><ce:abstract-sec id="as0005" view="all"><ce:simple-para id="sp0085" view="all">A cationic organic silicone surfactant (DTA) with specially designed functional groups was developed as a flotation collector for smithsonite. This surfactant was synthesized via the reaction between hexaethyldisiloxane and<ce:italic>N</ce:italic>-β-(aminoethyl)-γ-aminoisobutylmethyldimethoxy silane using tetramethylammonium hydroxide as a catalyst. Its flotation performance was validated by flotation tests using pure minerals. The results illustrated that DTA has strong collecting ability and better selectivity for smithsonite against quartz, calcite and dolomite compared to the traditional collectors such as octadecylamine, tetradecylamine and dodecylamine. Based on the analysis of FTIR spectra, zeta-potential measurements, X-ray photoelectron spectroscopy and density functional theory calculations, it can be concluded that the adsorption mechanism of DTA on the surface of smithsonite was mainly dominated by chemisorption and electrostatic adsorption. DTA's unique properties, which include two coordination sites (NH<ce:inf loc="post">2</ce:inf>and NH), and the “parachute” shape structure of OSi(C<ce:inf loc="post">2</ce:inf>H<ce:inf loc="post">5</ce:inf>)<ce:inf loc="post">3</ce:inf>, resulted in superior collecting powers for smithsonite.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" xmlns="http://www.elsevier.com/xml/ja/dtd" id="ab0010" class="author-highlights" xml:lang="en" view="all"><ce:section-title id="st0010">Highlights</ce:section-title><ce:abstract-sec id="as0010" view="all"><ce:simple-para id="sp0090" view="all"><ce:list id="l0005"><ce:list-item id="li0005"><ce:label>?</ce:label><ce:para id="p0005" view="all">A new surfactant DTA was synthesized as collector for smithsonite flotation.</ce:para></ce:list-item><ce:list-item id="li0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">DTA displays superior flotation performances than conventional amine surfactants.</ce:para></ce:list-item><ce:list-item id="li0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">DTA exhibits superior selectivity for smithsonite against gangue minerals.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
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